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Trophic relationships among native and exotic species produce novel direct and indirect interactions that can have wide-ranging community level effects and perhaps confer invasion resistance. We investigated whether native predators have the potential to directly limit the spread of the exotic mussel Mytilus galloprovincialis or mediate interactions among native and invasive mussels at a rocky intertidal invasion front in northern California. Lower survival of M. galloprovincialis in transplanted cultures exposed to predators indicated that the invader was more vulnerable to predators than the numerically dominant native M. californianus. Survival and per capita mortality rate in monocultures and polycultures did not vary for either M. galloprovincialis or M. californianus, suggesting that predator-mediated apparent competition and associational defense did not occur. Complementary laboratory feeding trials determined which among 3 intertidal predators preferred the exotic to 2 native species of mussel. The whelk Nucella ostrina was most selective, consuming the thinner shelled mussels (M. galloprovincialis and the native M. trossulus) rather than the thickershelled native species M. californianus. The crab Cancer antennaiius and the sea star Pisaster ochraceus showed no preferences among mussel species. N. ostrina were commonly observed among field-transplanted mussels; thus whelk prédation may be especially important in limiting the establishment of the invasive mussel. However, 15% of M. galloprovincialis remained intact in the field after 1 yr, suggesting that prédation alone may not inhibit establishment of the invader. A tenuous balance between larval settlement and early post-settlement prédation likely characterizes the invasion front. © Inter-Research 2009.

The article discusses a study which evaluates the effect of artificial seagrass on the predatory behavior of red drum, behavior of prey blue crab and mortality of three densities of the resource, hard clams, with emphasis on mechanisms of trait-mediated indirect effects (TMIE). Results suggest that the presence of red drum had a significant indirect effect on the clams through the change in behavior of the blue crab. It adds that the TMIE was not affected by the presence of seagrass. It concludes that the findings of the study demonstrate that a transient prey did not alter its home range in the presence of a predator or structure. Also noted is the implications of the results for interpretations of previous TMIE studies and risk taking models.

The article discusses research on the reef fish communities of a fully protected marine reserve in the Bahamas. It references a study by Robert W. Lamb at the Oregon State University in Corvallis, and his colleague, published in the June 3, 2010 issue of "Marine Ecology Progress Series." The researchers studied the relationship between the responses of species to body size and reserve protection, which may show the effects of trophic interactions among species and fishing selectivity. They conclude that substantial shifts in biomass distributions among trophic levels, size groups and species are caused by the indirect effects that propagate throughout the food web.

The article presents a study which investigates the relative and interactive effects of protection, system, distance to coral reefs, and seagrass presence on sea urchins in seagrass beds and coral reefs in Kenyan Lagoons. It mentions that multiple techniques have been used to test the hypotheses including the negative relationship between predation pressure and densities of the Tripneustes gratilla, apparent higher predation control and lower densities of urchins in protected areas, and apparent higher predation pressure and lower densities of urchins in seagrass sites close to reefs. It also presents the survey results for the effects of protection and area on sea urchins in coral reefs, and the effects of its protection.

The article discusses the study on non-native species' invasion to native predators on native and exotic prey species. It states that it is a worldwide epidemic which contributes to the communities' biotic globalization. It mentions that the Bodega Marine Reserve (BMR) in California becomes the study site of the conducted experiments. It notes that the study has incorporated bay mussels as materials for the experiment. It suggests that Mytilus galloprovincialis' limited establishment is contributed by predation as indicated by field and laboratory experiments.